The manufacture of optically active .alpha.-hydroxycarboxylic acids has hitherto been carried out by optical resolution of D,L-.alpha.-hydroxycarboxylic acids with resolving agents such as optically active amines; see for example J.Chem.Soc. (1906) 89, 935 relating to the optical resolution of D,L-lactic acid with morphine.
These known processes have, however, been found to be inefficient, especially because the resolving agents are costly and the separation is complicated.